Levitated objects can be rotated by controlling the relative phases of acoustic waves passing in different directions across the object. U.S. Pat. No. 3,882,732 by Wang et al. describes a method for rotating an acoustically levitated object lying in a chamber of square cross section, by controlling the relative phase of the waves used to levitate the object. The torque applied to the object depends upon the amplitude of the waves and the phase difference between them, with maximum torque being applied at a 90.degree. phase difference and zero torque at a 0.degree. phase difference. Although the torque on the object and consequently its rotation rate, can be controlled by adjusting the phase difference between the levitating waves, it has been found that at phase differences substantially different than 90.degree., liquid objects tend to become deformed. Such deformation does not occur at a 90.degree. phase difference, but such a large phase difference can produce excessively high rotation rates. A method and apparatus for controlling rotation of an object which avoids deformation of liquid objects while permitting close control of rotation and with relatively simple equipment, would be of considerable value.